substr() function (the first character has index 0).
<h4>Example substr()</h4>
<p>Click on the button to display the first 40 characters from the string in the JavaScript text variable.</p>
<button id='btn1'>Click</button>
<blockquote id='resp'>#resp</blockquote>
<script>
var text ='Extract the first 40 characters from this text - coursesweb.net/';
var resp = document.getElementById('resp');
document.getElementById('btn1').addEventListener('click', (ev)=>{
var str = text.substr(0, 40); // gets the first 40 characters
resp.innerHTML = str;
});
</script>
As you can notice in the example above, when we extract a specified number of characters, the last word can be chopped.
If you have a text from which you want to get a substring, and to add a button with "Read more ...", it's better to get the last word complete, as it is. In this case, instead of getting a number of characters, we'll extract a specified number of words.
The words are separated by space, so, we can use a RegExp (Regular expression) pattern to represent a string with a number of spaces according to the number of words we want to extract ( /([^ ]*[ ]{0,1}){1, nr}/ig ), then we apply t7he match() method with that RegExp to get the substring.
text.replace('/\s\s+/g', ' ') - replaces multiple whitespaces with a single space character, from "text".
<h4>Example extract a number of words</h4>
<p>Click on the button to display the first 6 words from the string in the JavaScript text variable.</p>
<button id='btn1'>Click</button>
<blockquote id='resp'>#resp</blockquote>
<script>
var text ='Extract the first 40 characters from this text - coursesweb.net/';
var nrw =6; // the number of words we want to extract
var rgxwords = new RegExp('([^ ]*[ ]{0,1}){1,'+nrw+'}', 'ig'); // regexp for specified number of spaces
var resp = document.getElementById('resp');
document.getElementById('btn1').addEventListener('click', (ev)=>{
var str = text.replace(/\s\s+/g, ' '); // replace multiple whitespaces whit single space
str = str.match(rgxwords)[0]; // get the substring with 'nrw' number of words
resp.innerHTML = str;
});
</script>
If the text-content contains HTML tags, when you extract a substring from that content, it is very posible to get opened tags, which will affect the content format when you add that substring in the page. In this case, it's better to remove the tags before extracting the number of characters, or words.
To remove HTML tags in JavaScript, you can use: text.replace(/\<[^\>]*\>/gi, '').
<h4>Example reemoving the tags from string</h4>
<p>Click on the button to display the first 35 characters from the HTML string in the JavaScript text variable.</p>
<button id='btn1'>Click</button>
<blockquote id='resp'>#resp</blockquote>
<script>
var text = 'Text content <em class="cls">with HTML tags</em>. Free courses for <b>web masters</b>: coursesweb.net/';
var nrw =6; // the number of words we want to extract
var rgxwords = new RegExp('([^ ]*[ ]{0,1}){1,'+nrw+'}', 'ig'); // regexp for specified number of spaces
var resp = document.getElementById('resp');
document.getElementById('btn1').addEventListener('click', (ev)=>{
var str = text.replace(/\<[^\>]*\>/gi, ''); // removes HTML tags
str = str.replace(/\s\s+/g, ' '); // replace multiple whitespaces whit single space
str = str.substr(0, 35); // gets the first 35 characters
resp.innerHTML = str;
});
</script>
<table><tr> <th>Title 1</th> <th>Title 2</th> </tr></table>
.some_class {
line-height: 150%;
}document.getElementById("id_button").onclick = function(){
window.open("http://coursesweb.net/");
}$ar_dir = scandir("dir_name");
var_export($ar_dir);